Vessel prosthesis, particularly for the replacement of aorta segments near the heart

ABSTRACT

The invention relates to a vessel prosthesis, particularly for the replacement of aorta segments near the heart, in the form of a pleated flexible tube with folds ( 3 ), the tube being configured as an arc, and the arc shape being fixed in an extension-resistant manner, in the non-implanted state, by means of extension limiters.

This is a Continuation Application of U.S. patent application Ser. No.10/497,848, filed Nov. 4, 2004, a National Phase Application filed under35 USC 371 of International Application No. PCT/EP02/14177, filed onDec. 13, 2002, an application claiming foreign priority benefits under35 USC 119 of German Application No. 101 62 821.8, filed on Dec. 14,2001, and claiming foreign priority benefits under 35 USC 119 of GermanApplication No. 102 42 153.6, filed on Sep. 5, 2002, the content of eachof which is hereby incorporated by reference in its entirety.

The invention relates to a vessel prosthesis, particularly for thereplacement of aorta segments near the heart.

Vessel prostheses for the replacement of hollow organs in humans andanimals, in particular of blood vessels, have been known for a longtime. They can be made of textile material (DE-A2 26 13 575, DE-A2 20 09349, DE-A124 61 370) and of non-textile material (cf. EP-A10 106 496,GB-A115 06 432).

Since the blood vessels, in particular the larger ones, have, along mostof their length, an approximately straight course through the body, thevessel prostheses also generally have the shape of straight tubes.

However, there are also vessels or vessel sections which have a curvedcourse. Thus, for example, the aorta in humans has an arched course inthe thoracic region just after the exit from the heart. In this regionit is divided into the following sections: The aorta originates from theleft ventricle with the first, ascending section (pars ascendens). Thispart merges into the aortic arch (arcus aortae), which in turn mergesinto the descending part of the aorta (pars descendens). All threesections have a more or less curved course, in particular the parsascendens and, most of all, the aortic arch. The pars descendens iscurved in particular at its start.

In the event of diseases, such as arteriosclerosis, or injuries in theregion of said curved aorta sections, heart surgery has hitherto ofteninvolved the use of straight vessel prostheses which are brought to thedesired arched shape by the operating surgeon during the operationitself. This has serious disadvantages for the operating surgeon and inparticular for the patient. On the one hand, it is awkward for anoperating surgeon to bring a straight vessel prosthesis to the desiredarched shape during the operation and then to sew it on to the naturalvessel ends. Much more serious, however, are the disadvantages for thepatient, since these prostheses exhibit buckling in the implanted state.This buckling occurs because the artificial aortic arch lengthensupward, in the event of an internal pressure, and as a result loses itsarc shape.

This buckling can form eddies, reduce the cross section of flow, andpossibly promote clots and thromboembolism. It therefore represents anot inconsiderable danger to the patients.

It is possible to produce pre-curved vessel prostheses from a textiletube material with pleats. To do so, straight sections can be drawn ontoa U shape and thermally fixed. These thermally pre-formed vessel archeshave the advantage that they are easier for an operating surgeon tohandle and to implant compared to the aforementioned straight vesselprostheses which have to be brought to the appropriate shape during theoperation itself. However, these thermally fixed vessel arches, in theimplanted state, exhibit similar buckling to that observed also in thestraight vessel prostheses.

From the monograph entitled Ischemic Heart Disease, 1999, page 398,Mosby/London, ISBN 0723429111, a vessel prosthesis is also known which,for fixing the arc shape, has on the inner side a row of individualstitches which provide for a partial gathering-together of the wall ofthe vessel prosthesis on the inner side of the arc. The thread ends ofthe individual stitches are each knotted to one another. However, thisvessel arch too has weaknesses due to shape changes in the implantedstate.

It is therefore an object of the invention to make available a vesselprosthesis which avoids the aforementioned shape changes, in particularbuckling, and, in the implanted state, even in the event of internalpressure, substantially maintains the full cross section of flow.

The object is achieved by a vessel prosthesis, in particular for thereplacement of aorta segments near the heart, in the form of a pleatedflexible tube with folds, the tube being configured as an arc, and thearc shape being fixed in an extension-resistant manner, in thenon-implanted state, by means of at least one continuous extensionlimiter running in the longitudinal direction of the vessel prosthesisand/or by a multiplicity of extension limiters running in the transversedirection. The folds of the pleating are gathered together to fix thearc. The gather preferably extends over a part of the tube circumferenceamounting to 10 to 180°, in particular 15 to 90°.

In contrast to the aforementioned pre-formed vessel arches which areonly thermally fixed and which, in the non-implanted state, can bebrought into a straight shape by pulling them, this is not possible inthe vessel prosthesis according to the invention.

A comparison between the known vessel prosthesis having individualstitches at the inner side of the arc and the vessel prosthesisaccording to the invention shows that the vessel prosthesis according tothe invention is also much more shape-stable than this known vesselprosthesis. The extension-resistant fixing, preferably provided orconfigured on the inner side of the arc, affords, in the implantedstate, a high degree of shape stability, particularly in cross section.By gathering together the folds of the pleat for fixing the arc over apart of the tube circumference, there is a marked increase in thestability of the arc shape. This in turn means that, in the implantedstate, there is a high degree of shape stability, particularly in crosssection. In contrast to the above-described vessel prostheses of theprior art, there is no twisting or widening of the arc, thus alsoavoiding the development of buckling.

In a particularly preferred embodiment of the vessel prosthesisaccording to the invention, the tube is configured as a thermallypre-fixed arc. This additional thermal pre-fixing ensures a furtherincrease in the stability of the arc shape. In addition, thegathering-together is easier to do on a thermally pre-fixed arc.

It is preferable for the vessel prosthesis according to the invention tohave a porous wall because this promotes the ingrowth of tissue andsmall blood vessels. It is particularly preferable that the vesselprosthesis is made of textile material and is in particular knitted orwoven. It is particularly preferable that the vessel prosthesis,particularly on the outside wall, is coated with a natural or syntheticabsorbable material. A suitable example is gelatin, in particularcross-linked gelatin. This material is slowly absorbed afterimplantation and replaced by endogenous tissue.

The vessel prosthesis according to the invention has, at least in thearched area, a fold-type pleating in the prosthesis wall. The pleatingcan be configured as a coil shape or as closed rings. Generally,pleating gives the vessel prosthesis elasticity and diameter stability.

The vessel prosthesis advantageously has 3 to 12, preferably 4 to 8, inparticular 6, folds per cm of prosthesis length. The folds of thepleating advantageously have a depth of 0.5 to 2.5 mm, preferably 1 to1.5 mm, which particularly in prostheses of greater diameter is greaterthan in prostheses of smaller diameter. In general, the fold depth is atleast 1 mm.

Starting from their peak, the folds on the outer side of the arcadvantageously enclose an angle of 70° to 110°, in particular of ca.90°.

To achieve the aforementioned extension resistant fixing of the arc, thefolds of the pleating are preferably fixed in a position close to oneanother at least on the inner side of the arc. To achieve stabilityagainst twisting of the vessel prosthesis, the latter can also have alateral fixing of the folds of the pleating. The fold spacings areadvantageously narrowest on the inner side of the arc and widen in thedirection of the sides of the arc. The folds of the pleating on theinner side of the arc are preferably so brought close together that theybear on one another on the inner side of the arc.

In a particularly preferred embodiment of the vessel prosthesisaccording to the invention, the folds of the pleating for forming andfixing an arc are permanently gathered together, in particular sewntogether, over a part of the tube circumference which amounts to 10 to180°, in particular 15 to 90°, along the tube circumference. The extentof the curvature is determined by the number of seams and the stitchspacing. Each fold of the pleating is preferably connected, inparticular sewn, to the next one, which ensures a high degree of shapestability. Each seam preferably comprises a multiplicity of stitches.

In a particularly preferred variant of the vessel prosthesis accordingto the invention, it has, as fixing means, at least one seam consistingof at least one thread, said seam having at least four, preferably atleast eight, through-runs of the prosthesis wall. For fixing the arc,the folds of the pleating are brought close together, in particular soas to touch each other, at least over a part of the tube circumference.In the present description, a seam is defined as one which has at leasteight through-runs and is formed from a continuous thread with threadstart and thread end. In this connection, a through-run is understood asa site where the sewing thread passes through the prosthesis wall.Thread start and thread end are preferably spatially separate from oneanother. A seam can have one stitch, several stitches or a multiplicityof stitches, for example cross-stitches and/or ride-over stitches.

In one embodiment of the invention, the vessel prosthesis according tothe invention has at least one seam having a multiplicity ofthrough-runs, in particular ca. 20 to 250 through-runs, the seam runningpreferably in the longitudinal direction and/or circumferentialdirection of the prosthesis. If the seam runs in the longitudinaldirection of the prosthesis, just one seam is enough to achieve asufficiently high degree of shape stability. By means of themultiplicity of continuous through-runs, a high degree of shapestability is achieved. Advantageously, the vessel prosthesis accordingto the invention is made extension-resistant at least on the inner sideof the arc. Fixing over a circumference width of 10° gives good resultsalready. Fixing over a width of 15° to 30° of the tube circumferenceaffords increased shape stability. To achieve the abovementionedextension-resistant fixing of the arc, the folds of the pleating arefixed in a position close to one another at least on the inner side ofthe arc. If only one seam is provided, this preferably has a width of at10° of the arc circumference. To achieve a further stability againsttwisting of the vessel prosthesis, the latter can also have lateralfixing of the folds of the pleating. The seams can run in thelongitudinal direction and/or transverse direction of the prosthesis.For this purpose, it is possible to provide widened seams or a number ofparallel seams. The fold spacings are preferably narrowest on the innerside of the arc and widen in the direction of the sides of the arc. Thefolds of the pleating on the inner side of the arc are preferablybrought so close together that they at least partially bear on oneanother on the inner side of the arc.

In one embodiment of the prosthesis according to the invention, at leastone continuous longitudinal seam is provided, in particular on a centralline of the inner side of the arc, in which case the thread runs over amultiplicity of stitches from one end of the gather to the other. Inthis way, all the folds are gathered together along one line, i.e. thefolds are gathered together without leaving a gap. As has already beenmentioned, this is not the case in the vessel prostheses of the priorart. Intermediate ties, in particular intermediate knots, between thefolds allow the prosthesis to be shortened or individual stitches to beremoved, without the whole seam coming unstitched.

In a preferred variant of the vessel prosthesis according to theinvention, at least one seam has cross-stitches, and in particularconsists of such. The stitches can be single, double or multiplecross-stitches. A seam, in particular a longitudinal seam,advantageously has between ca. 10 and 40, preferably between 20 and 30,stitches, preferably cross-stitches, per seam. Transverse seams are ingeneral shorter, since they cover at most 180° of the prosthesiscircumference. Their stitch count is ca. 10 to 20. Cross-stitches haveboth a longitudinal extent and also a transverse extent.

It is particularly preferable that seams, in particular seams havingcross-stitches, run in the circumferential direction of the prosthesis,in this case with preferably numerous parallel seams running in thecircumferential direction. They can extend over a width of theprosthesis which corresponds to ca. 5 to 50%, in particular ca. 10 to40%, of the total circumference of the tube. The seams running in thecircumferential direction can be connected to one another by acontinuous thread to form a continuous seam. Therefore, seams withcross-stitches can run in the longitudinal direction and/orcircumferential direction. This course of the seams in thecircumferential direction of the prosthesis provides for considerablewidening of the fixing, and the degree of gathering-together of thefolds is also increased. Compared to a vessel prosthesis in which onlyindividual points on the inner side of the prosthesis are gatheredtogether, this provides for a planar, in particular continuous course ofthe gathered areas. This affords a substantial increase in shapestability.

In a further embodiment of the prosthesis according to the invention, atleast one seam has ride-over stitches, and in particular consists ofsuch. The seams, in particular the seams consisting of ride-overstitches, preferably run in the circumferential direction of theprosthesis. Several seams, preferably parallel to one another, can bearranged running in the circumferential direction. These seams caneither be free or connected to one another. It is also possible toarrange several seams with smaller stitch count one behind the other inthe circumferential direction. In a particularly preferred embodiment,seams with small stitch counts are arranged both behind one another andalso alongside one another, running in the circumferential direction.The seams arranged alongside one another preferably have an identicalstitch count. This stitch count can be between 1 and 10, preferablybetween 1 and 3.

In a further preferred embodiment, at least one seam has onlythrough-stitches, and in particular consists exclusively of such. Thisseam variant is very easy to produce. The seam has at least eight,particularly preferably more than eight, through-runs. In the case wherethere are more than eight through-runs, the threads can be individuallytied, in particular knotted, between individual through-runs. At leastone seam advantageously has at least one thread which passes through thefolds of the pleating and runs the entire length of the gather. Thethread ends are preferably tied off, in particular knotted,individually. The thread advantageously has ties between the threadends, in particular every 1-2 pleat folds. Such a seam has the advantagethat it is very easy to produce.

The thread ends of a seam are advantageously arranged at a distance fromone another. The individual thread ends are preferably tied offindividually, in particular knotted.

In a particularly preferred variant of the vessel prosthesis accordingto the invention, the longitudinal seams have, between the thread ends,in particular every 2-3 pleat folds, ties, in particular knots, whichare preferably free of thread ends. These ties have the great advantagethat, despite continuous thread, the whole seam does not come unstitchedif the thread is cut through, for example during cutting of the vesselprosthesis to size by the operating surgeon. The thread can detach fromthe vessel prosthesis from the place where it is cut through to, at thevery most, the next tie. The ties preferably lie between the stitches.It is particularly preferable for each stitch to be followed by a tie.

Advantageously, two to six, in particular two to three, folds aregathered together in particular by a transverse seam.

In a preferred embodiment of the vessel prosthesis according to theinvention, it has several, in particular two, longitudinal seams whichare preferably substantially parallel and run across a multiplicity ofpleat folds. As in the abovementioned embodiment in which the stitchesrun in the circumferential direction of the prosthesis, this permitsgathering-together of the folds of the pleating over a greater area inthe circumferential direction. The parallel seams are preferablyarranged axially symmetrical to a line running in the center of theinside of the arc. Longitudinal seams can be combined with seams in thecircumferential direction of the prosthesis.

It is particularly preferable that the seams on the inner wall of theprosthesis do not lie substantially open, in particular the inner edgesof the pleating folds are free from thread material. The seamspreferably run only through the walls of the pleating and if appropriateover the outer edges thereof. In this way, the seams have only veryslight contact with blood, which for example reduces the risk ofthrombosis.

In a further embodiment of the vessel prosthesis, the folds of thepleating, for fixing the arc, are fixed in a position close to oneanother on the inner side of the arc by at least one strip, inparticular made of plastic, secured thereon. It is also possible thatsuch strips are also applied at the sides in order to achieve stabilityagainst twisting. Said strips are advantageously applied at leastpartially, in particular only, on the outside edges of the folds or thefold peaks. This means in turn that tissue and small blood vessels caneasily grow into the fold valleys, since at these places the pores arenot covered by the strip. In a preferred embodiment, said strips areadhesively bonded and/or sewn onto the vessel prosthesis.

In addition to the abovementioned preferred embodiments in which thefolds of the pleating are fixed in a position close to one another onthe inner side of the arc by being sewn together or by means of a stripbeing adhesively bonded or sewn on, it is also possible for the folds ofthe pleating to be fixed close together on the inner side of the arcalso by shrinking. For this purpose, it is possible to at leastpartially incorporate a high-shrinkage material, in particular ahigh-shrinkage yarn, into the wall of the vessel prosthesis.

The vessel prostheses according to the invention preferably have adiameter of 15 to 50 mm, in particular 20 to 40 mm. The diameter isgenerally chosen so that it corresponds to the natural diameter of thereplaced vessel. It is also possible for a vessel prosthesis accordingto the invention to be fitted in a person who is still growing, in whichcase, however, the vessel prosthesis will have to be changed from timeto time in order to adapt the diameter to the increasing diameter of thegrowing vessel.

The radius of the vessel arc in the longitudinal center axis of theprosthesis is advantageously 3 to 6 cm, in particular 4 to 5 cm. Thesevalues too depend on the anatomical circumstances of the patient.

Generally, the curve of the arc is adjoined at at least one end of thevessel prosthesis according to the invention, preferably at both ends,by a straight prosthesis portion. In the case of the aorta prosthesis,these straight portions correspond to at least parts of the parsascendens and/or pars descendens. These straight portions can also beunpleated.

The arc of the prosthesis advantageously encloses an angle of 120 to330, in particular 180 to 270°. The vessel prosthesis according to theinvention preferably has a conicity corresponding substantially to theconicity of the natural aorta.

All the larger blood vessels in the human body have branches. Thus,three blood vessels branch off from the aorta in the area of the aorticarch (the brachiocephalic trunk and the left common carotid and leftsubclavian arteries). To take account of these natural circumstances, apreferred embodiment of the vessel prosthesis according to the inventionhas artificial branches leading off from the vessel prosthesis andcorresponding to said branching vessels. Depending on requirements, andon anatomical circumstances, they can have different diameters andlengths. The length of these portions branching off from the prosthesisdepends in particular on the extent of the disease or injury of theaffected vessels.

For example, if only the aortic arch is affected by disease or injury,then it is also possible for the natural vessel branches to be sewndirectly onto openings in the vessel prosthesis, and the vesselprosthesis has no artificial branches. Said openings could either bealready provided in the prosthesis or could be cut out from theprosthesis wall by the surgeon during the operation itself.

In addition, the prosthesis can also be equipped with an attachment forreperfusion by means of the heart-lung machine.

The vessel prosthesis according to the invention can also havebifurcations (branches) and bulbi (widened areas).

Further details and features of the invention are set out in thefollowing description of a preferred illustrative embodiment inconjunction with the subclaims. The respective features can be realizedin isolation or in combinations with one another.

DESCRIPTION OF THE FIGURES

The drawings show the following:

FIG. 1: side view of a vessel prosthesis according to the invention madeof textile material, with sewn fixing.

FIG. 1 a: plan view of a cutout A from the central area of the crown ofthe arc of a vessel prosthesis according to the invention, with a seamconsisting of individual cross-stitches.

FIG. 1 b: plan view of a cutout from the central area of the crown ofthe arc of a vessel prosthesis according to the invention, with twoparallel seams consisting of individual cross-stitches.

FIG. 1 c: plan view of a cutout from the central area of the crown ofthe arc of a vessel prosthesis according to the invention, with twoparallel seams consisting of double cross-stitches.

FIG. 1 d: plan view of a cutout from the central area of the crown ofthe arc of a vessel prosthesis according to the invention, with a seamconsisting of multiple cross-stitches.

FIG. 1 e: plan view of a cutout from the central area of the crown ofthe arc of a vessel prosthesis according to the invention, with amultiplicity of seams consisting of ride-over stitches.

FIG. 2: enlarged side view of a vessel prosthesis according to theinvention, with sewn fixing.

FIG. 3: side view of a vessel prosthesis according to the invention madeof textile material, with fixing by means of a glued-on plastic strip.

FIG. 1 shows an arc-shaped vessel prosthesis according to the inventionmade of a textile material, with sewn fixing. A multiplicity ofdifferent seams are involved here. These are shown diagrammatically inFIGS. 1A to 1E. This prosthesis is suitable for replacement of arcuatevessels or vessel sections, in particular for the replacement of theaortic arch and parts of the pars ascendens and pars descendens. The arcof the tubular vessel prosthesis encloses an angle of 180°. Theprosthesis has a circumference of ca. 7 cm. Only the peaks of the foldscan be seen in FIGS. 1A to 1D.

In the area of the arched section 2 of the illustrated vesselprosthesis, the latter has a fold-type pleating in the prosthesis wall,the folds 3 of this pleating being configured as closed rings. The folds3 of the pleating are fixed in a position close to one another on theinner side 4 of the arc for fixing the arc. In the present illustrativeembodiment, this fixing is achieved by sewing together the folds over apart of the tube circumference along the inner side of the arc. Detailsof alternative seams are given in the descriptions of FIGS. 1 a to 1 e.The fold spacings are narrowest on the inner side 4 of the arc and widenin the direction of the outer side of the aortic arch 2. Adjoining thearched and pleated section 2 of the vessel prosthesis 1 at both ends,there are a straight portion 5 a and a straight portion 5 b. Thesestraight portions 5 have no pleating.

FIG. 1A shows a cutout A from the central area of the inner crown of thearc of a vessel prosthesis according to the invention. This vesselprosthesis has a seam 7 which runs in the longitudinal direction andwhich has a multiplicity of individual cross-stitches 8. The course ofthis seam is such that an imaginary center line 9 of the inner side ofthe arc extends substantially through the intersection points 10 of theindividual cross-stitches. The seam 7 has a base line 11 which connectsthe stitches 8 and along which the thread material extends along theentire gather of the pleating and connects the cross-stitches to oneanother and holds them on one another. The seam 7 additionally hasintermediate ties of the thread in the form of knots 12 which lie on thebase line. A knot follows after each stitch. The vessel prosthesis hasca. 3 stitches per cm. In total, there are 23 stitches provided alongthe length of the arc. Three folds of the pleating 3 are gatheredtogether by each stitch. Thus, each stitch comprises at least 12through-runs (per fold 4 through-runs of the prosthesis wall). The foldsare gathered together over a part of the tube circumference whichamounts to ca. 15°. The whole seam consists of a continuous thread.

FIG. 1B shows a cutout from the central area of the inner crown 9 of thearc of a vessel prosthesis according to the invention. In thisembodiment, two seams 13 a, 13 b run substantially parallel in thelongitudinal direction. The two seams have cross-stitches 14 which areconnected to one another by a base line 15 of thread material whichholds the individual stitches on one another and thus likewisecontributes to the gather. The thread material on the base line hasknots 16, with a knot following after each stitch. The stitches run ca.6 mm in the circumferential direction of the prosthesis. The two seamsare arranged approximately axially symmetrically parallel to the line 9.Each seam has between 20 and 25 stitches. Each seam 13 a and 13 b hasca. 3 to 4 cross-stitches per cm of prosthesis length. Either two orthree folds of the pleating are gathered together per cross-stitch. Asin FIG. 1 a, each stitch comprises at least 12 through-runs. Thestitches of the two seams do not lie directly opposite one another, butare in each case offset relative to one another by one pleat fold. About90° of the tube circumference is included by the outer edge of the firstseam and the outer edge of the second seam. Between the two seams, inthe inner area of the arc, the folds bear close on one another.

FIG. 1C shows a cutout from the central area of the crown of the arc ofa vessel prosthesis according to the invention. This embodiment has,like the embodiment in FIG. 1 b, two parallel seams 17 a and 17 brunning in the longitudinal direction. The embodiment in FIG. 1C isidentical to the embodiment in FIG. 1B, with the following exceptions:The stitches are double cross-stitches 18; the stitches of the two seamslie opposite one another, as a result of which the stitches lyingopposite one another gather together the same folds (in the inner sideof the arc in each case 3 folds, and in the outer area at the arc endsin each case 2 folds); the knots lie for the most part in the area ofthe stitches. Each double cross-stitch, which gathers together 3 folds,comprises 16 through-runs (6 through-runs each of the two outer folds,and 4 through-runs of the middle fold). Each double cross-stitch, whichgathers together 2 folds, comprises at least 18 through-runs.

FIG. 1D shows a cutout from the central area of the crown of the arc ofa vessel prosthesis according to the invention. This embodiment has aseam 19 which has numerous parallel multiple cross-stitches 20. Thesemultiple cross-stitches have a different number of individualcross-stitches. This number ranges between 11 and 16 stitches. Themultiple cross-stitches protrude right and left beyond the base line 21and run in the circumferential direction of the vessel prosthesis. Indoing so, they gather together the folds of the pleating over a part ofthe tube circumference amounting to between 100 and 160°. Extending onthe base line, approximately in the central line 9, there is a threadwhich connects the individual transverse seams to one another and ineach case is a part of the Continuous thread material forming the seams.By means of the longitudinal connection of the individual transverseseams, the overall combination of the seams is given a planar character.Per multiple cross-stitch, 3 folds per stitch are gathered together inthe central area of the arc (crown area), and, in the outside areas ofthe arc 2, folds are gathered together per multiple cross-stitch. Theindividual multiple cross-stitches run approximately parallel to oneanother. The present embodiment has 24 multiple cross-stitches and hasca. 4 multiple cross-stitches per cm of prosthesis length. Thisembodiment also has knots 16 which are located substantially in the areaof the multiple cross-stitches. There are at least as many intermediateknots as there are multiple cross-stitches.

FIG. 1E shows a cutout from the central area of the crown of the arc ofa vessel prosthesis according to the invention. In contrast to thepreviously described embodiments, several parallel seams run in thelongitudinal direction of the prosthesis, namely one along the innercrown 9 and in each case two seams to the right and two to the leftthereof. The longitudinal seams have a width of at least two, preferablytwo to four, stitches and are divided in the longitudinal direction intoa multiplicity of individual transverse seams arranged in rows. Theseams of this embodiment have ride-over stitches 22. The threads of theindividual seams have knots 16 at their ends. Along the central mid-line9 there is a row of individual seams 23 with single ride-over stitches.These individual seams 23 are not connected to one another. In bothdirections in the circumferential direction of the vessel prosthesis,each individual seam 23 with single ride-over stitch is followed, at adistance of ca. 4 mm, in each case by a seam 24 consisting of tworide-over stitches. These individual seams run in the circumferentialdirection of the vessel prosthesis. The individual seams 23 and theseams 24 with two ride-over stitches are located in rows along theprosthesis. The threads of said individual seams 24 have knots 16 attheir ends. These seams 24 with two ride-over stitches are followed, inthe circumferential direction and at a distance of ca. 7 mm, by furtherindividual seams 25 which all have three ride-over stitches. The threadsof these individual seams too have knots 16 at their ends. Theindividual seams 25 lie approximately on a line in the circumferentialdirection, with in each case an individual seam 24 with two ride-overstitches and one seam 23 with a single ride-over stitch. Therefore, fiveseams lie substantially one behind the other in the circumferentialdirection (two seams with three ride-over stitches, two seams with tworide-over stitches, and one seam with single ride-over stitch). Theindividual seams 25 also lie in longitudinal rows. By the individualseams lying behind one another on lines in the circumferential directionand in rows in the longitudinal direction, the folds of the pleat aregathered together flat. Seams with single ride-over stitches comprise 8through-runs, seams with two ride-over stitches comprise 12through-runs, and seams with three ride-over stitches comprise 16through-runs. For the sake of clarity, the folds are not shown in thepresent figure. Here, the folds of the pleating for fixing the arc aregathered together over a part of the tube circumference amountingapproximately to 180°. This embodiment has, in the longitudinaldirection, ca. 30 single ride-over stitches and thus ca. 60 seams withtwo ride-over stitches (in each case 30 alongside one another in thelongitudinal direction) and ca. 60 seams with three ride-over stitches.

FIG. 2 also shows a vessel prosthesis 26 according to the invention madeof a textile material with sewn fixing. The seam in this case involves avariant type which is very easy to produce. This seam has a continuousthread 27 running centrally in the longitudinal direction and passingthrough the folds 3 of the pleat. The thread 27 has ties 28, e.g. knots,at its ends. These ties 28, on the one hand, permit gathering on theinner side 4 of the arc, and, on the other hand; said ties permit fixingof the thread 27 in the prosthesis 26. The seam comprises twothrough-runs 6 per fold. The seam, which is a longitudinal seam, alsohas ties 29, in particular knots, between the thread ends. These knotsare located in each fold 3 of the pleating. As in the variants alreadydescribed above, these knots 29 prevent unraveling of the seam in theevent of the latter possibly being cut through.

Said ties (knots) 29 can also be somewhat less numerous and, forexample, can be present only in every second or third fold. As hasalready been mentioned above, the main advantage of this seam is that itis easy to produce. Several such seams can also lie parallel alongsideon another.

This embodiment too has an arched part 2 with pleating, both ends of thearc being adjoined, respectively, by straight, unpleated sections 5 aand 5 b.

FIG. 3 shows a vessel prosthesis 30 according to the invention, likewisemade of a textile material. This prosthesis too is suitable for the useof arched prostheses or vessel portions, in particular for thereplacement of the aortic arch and areas of the pars ascendens and parsdescendens. The arc of the vessel prosthesis shown encloses an angle of180°. In the area of the arched portion 2 of the vessel prosthesisshown, the latter has a fold-type pleating in the prosthesis wall, thefolds 3 of this pleating being configured as closed rings. The folds 3of the pleating are fixed in a position close to one another on theinner side 4 of the arc for fixing the arc. In the present illustrativeembodiment, this fixing is obtained by an extension-resistant plasticstrip 31 bonded adhesively onto the fold peaks of the inner side of thearc. The fold spacings on the inner side 4 of the arc are narrowest andthey widen in the direction of the outer side of the aortic arch.Analogously to the illustrative embodiment in FIG. 1, the arched andpleated portion 2 of the vessel prosthesis 7 is adjoined at both ends ofthe arc by, respectively, straight portions 5 a and 5 b. These straightportions 5 a and 5 b have no pleating.

Tests comparing the vessel prostheses according to the invention withvessel prostheses from the prior art have shown that, when the internalpressure increases, the shape of the vessel prostheses according to theinvention remains stable. By contrast, in vessel prostheses from theprior art, it has been observed that, when the internal pressureincreases, these substantially deform and exhibit buckling.

The invention claimed is:
 1. A vessel prosthesis for the replacement ofaorta segments near the heart comprising a pleated flexible tube withfolds, the tube being configured as an arc, the arc shape being fixed inan extension-resistant manner, in the non-implanted state, by means ofat least one continuous extension limiter running in the longitudinaldirection and/or a multiplicity of extension limiters running in thetransverse direction, and the folds of the pleating being gatheredtogether to fix the arc, wherein the prosthesis has, as an extensionlimiter, at least one seam with at least eight through-runs, the atleast one seam running in the longitudinal direction and/or in thecircumferential direction of the prosthesis, and wherein the at leastone seam in the longitudinal direction has at least one continuousthread with thread ends, the at least one continuous thread running atleast on the inner side of the arc, passing through the folds of thepleated tube and having, between the thread ends, intermediate ties. 2.The vessel prosthesis of claim 1, wherein the pleated tube is configuredas a thermally pre-fixed arc.
 3. The vessel prosthesis as claimed inclaim 1, wherein folds of the gathered pleating extend over a part ofthe tube circumference amounting to 10 to 180°.
 4. The vessel prosthesisas claimed in claim 1, wherein at least one seam is located on a centralline of the inner side of the arc.
 5. The vessel prosthesis as claimedin claim 1, wherein at least one seam has cross-stitches.
 6. The vesselprosthesis as claimed in claim 1, wherein at least one seam has betweenca. 10 and 40 stitches per seam.
 7. The vessel prosthesis as claimed inclaim 1, wherein at least one seam has through-stitches.
 8. The vesselprosthesis as claimed in claim 1, wherein thread ends are arranged at adistance from one another.
 9. The vessel prosthesis as claimed in claim1, wherein the thread ends are tied off individually.
 10. The vesselprosthesis as claimed in claim 1, wherein in each case 2 to 6 folds aregathered together by a transverse seam.
 11. The vessel prosthesis asclaimed in claim 1, wherein it has several longitudinal seams which runacross a multiplicity of pleat folds.